A self-expanding prosthesis such as a stent may be introduced into a patient's body using a delivery device that includes a push-pull mechanism with an outer catheter coaxially slidably disposed over an inner catheter. The prosthesis is disposed in a circumferentially-restrained configuration at the distal end of the device between the inner catheter and the outer catheter. The prosthesis may be deployed by proximally pulling back the outer catheter relative to the inner catheter, exposing the prosthesis and allowing it to deploy/circumferentially expand.
The push-pull delivery device described above may have several shortcomings. For example, when using this conventional push-pull delivery device, a physician may inadvertently retract the outer catheter too far and prematurely deploy the prosthesis in an incorrect position within a body lumen. In that circumstance, repositioning the prosthesis may be difficult, if not impossible, because the prosthesis already will have radially self-expanded and engaged the body lumen.
Accordingly, there is a need for a delivery system that can increase the control, accuracy and ease of placement during deployment of a prosthesis. The embodiments described below may be useful for increasing the control, accuracy and ease of placement during deployment of the prosthesis and may also solve other problems.